"They get on me making sure I'm doing everything the right way," he told PEOPLE Wednesday at a press event for OraQuick, the first at-home HIV test kit. Johnson, 53, says his family constantly asks, " 'Are you taking your meds, are you working out, are you eating healthy?' "

His family "is in the same fight, the same battle in terms of HIV," he says, "I think it's brought my whole family closer together."

In addition to that support system, Johnson credits regular workouts, a positive attitude and his trio of drugs for keeping him healthy.

"Many people are surprised to find that for 21 years the cocktail I've been taking [is] the same three drugs, once a day," he says, "the thing that's made Magic magical is that I've taken my meds!"

Still, his family's support is critical. "Nobody can beat this disease by himself," he adds. "You need a support system that you can open up to."